The Bishkek vertical array (BIVA): acquiring strong motion data in Kyrgyzstan and first results

We present results from a vertical array of accelerometers that was recently installed in Bishkek (Kyrgyzstan) with the long-term aim of recording strong motion data. Taking advantage of recordings of a Mb 4.7 earthquake that occurred 40 km from the array site during the installation phase, we provide results of some preliminary data analysis. First, estimates of the S-wave velocity and Qs structure are deduced by the inversion of the deconvolved wavefield between the sensors in the borehole. Furthermore, the application of the nonstationary ray decomposition Kinoshita (Earth Planets Space 61:1297-1312, 2009) allowed at least three reflectors in the shallow velocity structure below the array to be identified. The complex nature of the wavefield (with up-going, down-going waves, and converted phases) due to the coarse, unconsolidated subsoil structure is highlighted by means of numerical simulations of ground motion.